Gas-fired portable heaters are used in multiple environments. The heater typically includes a housing having a combustion chamber. The housing has an inlet for receiving air into the chamber. A mixture of fuel and air is introduced into the chamber where combustion occurs, to provide a heat. Often, a plenum directs the heat toward a heating surface, to distribute it over the surface thereof.
These types of heaters are often used for outdoor use due to the emission of carbon monoxide and other potentially harmful combustion products. Prior designs of these types of heaters are typically not considered safe for operation in an enclosed environment, such as small recreational enclosures, including tents, truck-caps, fishing huts, trailers, vans, etc. These prior designs may not meet safety certification targets regarding combustion requirements (e.g., release of combustion products) at a high and low firing condition and at a reduced pressure, or other safety requirements.